Mercury 150 powerhead removal (stuck)

[ndf203]

I have a 1983 Mercury 150 Black Max I a m trying to remove the powerhead off of and cannot even budge it! I have already removed the lower unit and have sprayed Kroil all over the bolts and around the motor and it will not move. Can anyone tell me how to seperate the powerhead so I can replace a piston? I have all of the bolts out.

[Scream And Fly]

You can try gentle heat while using lifting force from a cherry picker. Make sure you're using a flywheel lifting ring. Also, try PB Blaster on the powerhead studs and let it sit overnight.

Welcome to the forums!

Greg

[drasticplastic]

Ditto on the pb blaster (awesome stuff). Have upward tension on the powerhead via lift ring soak with blaster and waite. should pop loose overnight. If not add some heat like Greg said. Do make shure that you have the 2 front nuts off, they are kinda hidden. They are located up under by the steering pivot. Good luck.

[MaxPower]

If all else fails, the cheapest is to sacrifice the adaptorplate (the part between the block and the midsection) and cut the longest studs. Carefully cut into the adaptorplate with a thin bladed grinder, just enough to cut the studs. Then you can lift off the powerhead and replace defective studs and the adaptorplate. Sounds quite hairy, but it works. If you are lucky, the adaptorplate could be repaired by a skillful welder..
Good luck!!

[Hydrasports205]

before you do that make sure you've got all the bolts off

there are 10 - 4 long studs, 4 shorts around the back, and the 2 up front by the steering arm like drastic said - pretty common for people to miss those.

btw - pb blaster is the cat's a**. Use it on any old bolts or studs you've got to deal with. It'll make life much easier....mucho good advice from greg and drastic.

[Markus]

Another thing to try in combination with the other:

Try to figure out which stud is stuck. Then put a nut on it and something below it. Drive the nut downwards onto the surface below to push the stud and powerhead upwards.

[Hydrasports205]

you can also beat on everything with a hammer - and if it doesn't pop loose just get a bigger hammer - just kiddin.

[drasticplastic]

NDF any luck gettin that thing off there ?.

[vdoh8687]

before you do that make sure you've got all the bolts off

there are 10 - 4 long studs, 4 shorts around the back, and the 2 up front by the steering arm like drastic said - pretty common for people to miss those.

btw - pb blaster is the cat's a**. Use it on any old bolts or studs you've got to deal with. It'll make life much easier....mucho good advice from greg and drastic.

Hey, so I hate to post in an old thread (especially for my first post), but I am having the same issue as OP. Currently I've got the engine under tension with an engine crane/lifting eye and I sprayed everything with PB blaster. I got 8 nuts off, and two nuts in the front are mostly off, they are hitting part of the steering now so I need to the engine to break loose and lift a bit. Any other suggestions? The lower unit and tilt trim are both off, any all the wiring and hoses are disconnected. I'll post some pics, did I remove all the necessary bolts?

Its and 86 Blackmax 150, and I am pulling the power-head because I suspect the exhaust plate gaskets are blown (mechanic said same thing and quoted 10 hours of labor/anticipated broken bolts/studs). Also, if anyone else is reading this in the future, soaking stuck bolts in PB blaster is helpful, as is clearing any rust off the exposed threads with a Dremel and wire brush attachment and heating it with a propane torch.

Thanks in advance.344302344303344304

[Hydrasports205]

Looks like you've got everything loose that needs to be....looks like that engine has seen some salt and that corrosion makes everything harder. I wouldn't go crazy with it but you might be able to try threading the nuts back on a little and prying against them to help pop it loose. Like I said don't go crazy and break something but I think I've had to do that before.

[vdoh8687]

Looks like you've got everything loose that needs to be....looks like that engine has seen some salt and that corrosion makes everything harder. I wouldn't go crazy with it but you might be able to try threading the nuts back on a little and prying against them to help pop it loose. Like I said don't go crazy and break something but I think I've had to do that before.

Thanks or the reply, I will keep working on it, and yes it has been in saltwater its entire life, with just a rebuild in 1990. I've had it for 3 years, and it was not well taken care of before that. Good compression/leak down test though, and I replaced the starter, coils, plug wires and rebuilt the carbs, then had the stator, rectifier, wiring harnesses, and switch boxes replaced so hopefully I can get this sorted out or I'm out all that work (though that was 2 seasons ago so its not a complete loss). I am going to replaced any hardware I'm taking off, maybe even the studs if I can get them out. I'll post pics/notes if and when I get it apart so that might help someone else.

[W2F a V-King]

As mentioned above...PB and heat. Don't believe propane will get enough heat going.
Acetylene Oxygen is better to get concentrated heat where it needs to be. BUT !! You need to be careful heating aluminum with torches...one minute it's all good...then it's not.

At any rate the power head needs to come off anyway.

Put plenty of "lift" on the power head with your hoist, try to keep the angle of the dangle pulling straight up. Leave it under stress for as long as it takes to get it to pop up.

PB..Heat..PB..Heat...etc.
It's probable it's one or more of the rear 8 bolts, not the ones under the power head, as most carb motors leak/spill fuel from carbs when motor gets tilted, and that area of the motor tends to stay lubed up.

If you have an air compressor and an impact hammer with a flat nose bit, some "Gentile" tapping along the housing vertical inline with the bolts might help break the frozen grip of corrosion.

Any disfiguring of the driveshaft housing or Midsection can be addressed after you get the power head off and repaired.

Might want to coat the new or cleaned up studs and holes in the mid with some kind of corrosion protection.
I don't care for never seize in salt water motors.

HTH

James

[vdoh8687]

As mentioned above...PB and heat. Don't believe propane will get enough heat going.
Acetylene Oxygen is better to get concentrated heat where it needs to be. BUT !! You need to be careful heating aluminum with torches...one minute it's all good...then it's not.

At any rate the power head needs to come off anyway.

Put plenty of "lift" on the power head with your hoist, try to keep the angle of the dangle pulling straight up. Leave it under stress for as long as it takes to get it to pop up.

PB..Heat..PB..Heat...etc.
It's probable it's one or more of the rear 8 bolts, not the ones under the power head, as most carb motors leak/spill fuel from carbs when motor gets tilted, and that area of the motor tends to stay lubed up.

If you have an air compressor and an impact hammer with a flat nose bit, some "Gentile" tapping along the housing vertical inline with the bolts might help break the frozen grip of corrosion.

Any disfiguring of the driveshaft housing or Midsection can be addressed after you get the power head off and repaired.

Might want to coat the new or cleaned up studs and holes in the mid with some kind of corrosion protection.
I don't care for never seize in salt water motors.

HTH

James

Tried PB blaster, tried propane, tried leaving it under tension and banging on the studs and around the studs with a hammer and no luck. Tried pushing up on the studs with a 3' crow bar, and I also tried putting some of the nuts back on the studs, then sliding a spacer under the stud and backing the nut back off so it would push up on the spacer, and no luck. Put a 6' solid steel rod through the eyelet (similar diameter to the eye) and tried levering it loose and the eyelet just started to bend. A shop in the area who rebuild old engines said they have seen the problem and could probably get it off, but said it would cost $500-1200 just to get it off. Then I still have to replace all the gaskets and replace or rebuild the trim pump. At this point I think I might just look at an injected used engine from the early 2000s, which is unfortunate as the engine was running really nicely last season. Hopefully someone else has some luck with some of these ideas.

[rayhawk]

A propane torch is not enough. You won't get it off without an oxy-acetylene torch. The (4) long studs in the front on either side need to be broken loose. Buy some 3/8-24 jam nuts, tighten them against each other, then try to loosen each long stud in the front, one at a time. Only try to loosen the stud immediately after heating the midsection/exhaust plate with the torch. The majority of corrosion occurs where the stud exits the midsection, so focus your heat there. If the paint isn't gone, you aren't getting it hot enough. If the nuts spin, re-tighten and apply more heat, then more pb blaster, then repeat. I spent several hours on just one stud, and I managed to save everything but the studs. I found that once the stud starts to back out, that is good enough to lift the powerhead, you don't have to get it completely loose from the block (although that is ideal if you can). Don't use any prybars, you will just end up breaking something. Good luck and be patient.

[Phil Conant]

Put a galvanized pipe under the cherry picker legs then chain or cable the bottom engine yoke to the pipe under/between cherry picker legs. This will hold the engine from trying to be pulled up when your lifting on the powerhead. Your cherry picker will turn into a hydraulic spreading monster. This always works. Use high quality chain/cable eye protection, move on lookers a safe distance back. You may want to wear a hard hat too. Pump hydraulic jack handle standing as far back as you can.

Good Luck !

[Go Time]

If Phils plan doesn work with adding in the heat, you can try drilling through the 4 long studs in the upper adapter plate, which is where the problem is using a 1/2 inch bit. This will cut the studs in half, freeing the power head and allow you to recover the adapter plate.

[Tripps]

That's a good idea Phil I never did that but its like pumpkin chunkiness I just did one and the studs broke the block apart,it was junk anyway I got two wedges from a welding supply shop that go from zero to 250 in 6 inches ,they apply so much pressure its unreal ox and acetic work but the rubber on mid usually burns. Up its always a challenge drilling the mid a inch under the pwrhd. Is a good idea but I never had to do it .I also use a 6 ft prybar that fits right on back studs and mid and get it moving then things start to happen .having trips on a older boat I learned alto!!!

[vdoh8687]

Put a galvanized pipe under the cherry picker legs then chain or cable the bottom engine yoke to the pipe under/between cherry picker legs. This will hold the engine from trying to be pulled up when your lifting on the powerhead. Your cherry picker will turn into a hydraulic spreading monster. This always works. Use high quality chain/cable eye protection, move on lookers a safe distance back. You may want to wear a hard hat too. Pump hydraulic jack handle standing as far back as you can.

Good Luck !

This sounds like a good idea, I was worried about damaging my engine bracket and I think this would have prevented it. I got it off this morning with some friends, we used MAP gas instead of propane (would have tried oxy next). With the MAP gas we had 2 guys heating the areas of the long studs (1 on each side) and 2 guys prying under the bolts with pry bars. Once it started to come loose, we used rear axle wedges work it up a little at a time and kept spraying with PB blaster. We also rocked it back and forth with pry bars. It was under tension from an engine crane the whole time. The pry bars put 2 small dents in the plate under the power head when rocking it, but it doesn't look like anything that cant be filled in, they are not in the area where the exhaust or water flow through so it should hopefully be fine. Hopefully I can get it going in the next week. The biggest questions is whether or not the threads on the studs got too damaged.